Born-Oppenheimer breakdown and non-adiabatic lifetimes of rovibrational levels of D2 lying near the n = 2 dissociation limit: Experiment and theory

► EF levels of D2 are excited in two steps from the ground state, then fluoresce. ► The measured lifetimes disagree strongly with adiabatic ab initio calculations. ► The reason - EF levels are strongly mixed with other singlet gerade states. ► Accounting for this non-adiabatic mixing improves agreement with experiment. ► Strong rotational variation of lifetimes results from accidental near-resonance.